Field Test Results of Green Roofs, Cool Roofs, and Conventional Roofs CNY Engineering Expo Oncenter, Syracuse, NY November 9, 2015

Transcription

1 Field Test Results of Green Roofs, Cool Roofs, and Conventional Roofs CNY Engineering Expo Oncenter, Syracuse, NY November 9, 2015 Hugh I. Henderson, Jr. P.E CDH Energy Corp. Cazenovia, NY

2 Project Goals Side-by-Side Comparison of Different Roofing Systems EPDM w/ 4 inches of foam (UNIT 1) TPO w/ 4 inches of foam (UNIT 2) Vegetative Roof with 4 inches (UNIT 3) TPO w/ 8 inches of foam (UNIT 4) Measure Performance Impacts Compare thermal losses / energy impacts Compare water retention performance Jamesville provided 4 similar roof applications

3 Four Different Roofs at the Same Facility Unit 4 TPO, 8 in Unit 3 Veg, 4 in Unit 2 TPO, 4 in Unit 1 EPDM, 4 in

4 Approach Install dataloggers to continuously monitor performance Two independent measurement locations on each roof Collect data continuously at 15-minute intervals Directly measure temperature differences through roof assembly Measure weather conditions Direct measurement of HVAC energy use was not practical at this site

5 Roof Assemblies Location Insulation Surface Unit 1 4 inches Poly Iso 1 foam board EPDM rubber 2 (R22) Unit 2 4 inches Poly Iso 1 foam board TPO White 3 (R22) Unit 3 4 inches Poly Iso 1 foam board (R22 + vegetative laver) EPDM w/ Vegetative Surface Unit 4 8 inches Poly Iso 1 foam board (R45) TPO White 3 Notes: 1- Polyisocyanurate foam board applied in 2 inch layers 2- Black EPDM (Ethylene Propylene Diene Monomer) single-ply rubber roof membrane 3- White TPO (Thermoplastic Polyolefin) roof membrane

6 Vegetative Roof Carlisle Roof Garden System Light-weight assembly

7 Instrumentation Point Description Instrument Eng Locations Units TRO Roof Temperature Type-T ºF At each station (on top of insulation, under roof brd) Thermocouple TRI Roof Temperature Type-T ºF At each station (under roof insulation, above deck) Thermocouple TAI Indoor Temperature (just below the roof) Type-T Thermocouple ºF At each station Point Description Instrument Eng Locations Units TAO Outdoor Temperature Type-T ºF Station 2A Thermocouple ISH Solar Insulation Licor LI200x W/m 2 Station 2A (horizontal) TGR Green Roof Temperature Type-T ºF Station 3A (in middle of soil layer) Thermocouple MGR Green Roof Moisture Content Campbell 0-1 Station 3A (in middle of soil layer) Scientific CS616 RAIN Rainfall Texas Inches Station 2A Electronics 525 WF Water Flow from Green Roof Mockup Hydrolynx 5050 Gal/h Station 2A

8 Roof Sensor Location/Station Thermocouple TRO Thermocouple TRI Thermocouple TAI

9 Sensors Installed During Construction Thermocouple Probe Insulation Board

10 Thermocouple on Top of Insulation (station 1B)

11 Indoor Thermocouple

12 A & B Stations on Each Unit 1A 1B

13 Results for Sunny November Day 80 Unit 3: 4 in, Veg 80 Unit 4: 8 in, TPO Temperature (F) Temperature (F) Insolation Temperature (W/m^2) (F) EPDM TPO Unit 1: 4 in, EPDM Unit 2: 4 in, TPO Ambient Temperature, Top of Insulation, 10 Bottom of 8Insulation, 9 Indoor Temperature Heat Loss Temperature (Btu/ft^2-h) (F)

14 Heat Transfer Analysis Veg roof (optional) TAO Deck Board membrane Insulation Board TRO R insulation q Where: R insulation q - R-value for Insulation layer (ºF-h-ft 2 /Btu) - Heat flux through the roof assembly (Btu/h-ft 2 ) Concrete Deck TRI TAI q = (TRI-TRO) R insulatiion

15 Impact on Heat Transfer (solid line = station A / dotted line = station B) 1.5 Insulation Layer 1.0 Heat Loss Rate (Btu/ft^2-h) Unit 1: 4 in, EPDM Unit 2: 4 in, TPO -1.0 Unit 3: 4 in, Veg q = (TRI TRO)/R ins Unit 4: 8 in, TPO Nov 2009

16 Summer Sunny, 71F pk May Summer, Sunny, 71F 2 Summer, Sunny, 71F Temperature (F) Heat Loss (Btu/ft^2-h) (F) Summer, Sunny, 59F Summer, Sunny, 59F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO ft^2-h) 4 2

17 Tempera Summer Sunny, 59F pk -2 May Heat Loss ( Temperature (F) Summer, Sunny, 59F Heat Loss (Btu/ft^2-h) Summer, Sunny, 59F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO

18 Summer Cloudy, 44F pk May 12 Temperature (F) Summer, Cloudy, 44F Heat Loss (Btu/ft^2-h) Summer, Cloudy, 44F F) Fall, Sunny, 38F Fall, Sunny, 38F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO ^2-h) 3 2

19 Temperatu Fall Sunny, 38F pk 0 Nov Heat Loss (Bt Fall, Sunny, 38F 3 Fall, Sunny, 38F Temperature (F) Heat Loss (Btu/ft^2-h) Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO

20 Winter Sunny, 3F pk Jan Winter, Sunny, 3F, Min temp of -13F 3.5 Winter, Sunny, 3F, Min temp of -13F Temperature (F) Heat Loss (Btu/ft^2-h) F) Winter, Cloudy, 25F Winter, Cloudy, 25F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO ^2-h)

21 Tempe Winter Cloudy, 25F pk Heat Loss Jan Temperature (F) Winter, Cloudy, 25F Heat Loss (Btu/ft^2-h) Winter, Cloudy, 25F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO

22 Spring Rainy, 41F pk Apr 17 Temperature (F) Spring, Morning, 41F Heat Loss (Btu/ft^2-h) Spring, Morning, 41F Rain re (F) Spring, Sunny, 49F Spring, Sunny, 49F Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO u/ft^2-h) 4 2

23 Impact of Snow & Rain 30 Temperature (F) Ambient Nov Dec Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO Heat Loss (Btu/ft^2-h) Nov Dec Water (inches) Rain Snow (no drainage) Rainfall Drainage

24 Daily Heat Loss Impact of Snow Cover Unit 1: 4 in, EPDM Unit 2: 4 in, TPO Unit 3: 4 in, Veg Unit 4: 8 in, TPO Heat Loss (Btu/ft^2-day) 20 0 Heat Loss Heat Gain Outdoor Temperature (F)

25 Monthly Heat Loss Heat Loss (Btu/ft^2) Month Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO November December-09 1, , , January-10 1, , , February , March April May-10 (178.1) June-10 (261.0) July-10 (437.9) (22.2) August-10 (302.7) September-10 (8.8) October November December , , January , , February , Htg Season 4, , , ,366.6 (Oct to April) 1, ,147.4 (518.8) 30% 23% -11% 2010 Clg Season (1,188.5) , (May to Sep) 1, , ,886.5

26 Monthly Heat Loss 1,400 1,200 1,000 Unit 1: 4 in EPDM Unit 2: 4 in TPO Unit 3: 4 in Veg Heat Loss (Btu/ft^2) (200) Heat Loss Heat Gain Unit 4: 8 in TPO (400) (600) Jan-10 Feb-10 Mar-10 Apr-10 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Dec-10

27 Seasonal Cost Analysis Heating Season Assumptions: 80% efficient, $1 per therm Cooling Season Assumptions: 0.9 kw per ton, 12 per kwh

28 Heating and Cooling Costs HEATING Annual Heat Load (MMBtu per 1000 sq ft) Annual Gas Use (therms per 1000 sq ft) Annual Cost per 1000 sq ft Savings per 1000 sq ft Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO $ 61 $ 80 $ 75 $ 55 $ (18) $ (14) $ 6 COOLING Reduced Cooling (ton-hrs/yr per 1000 sq ft) Reduced Cooling Power (kwh/yr per 1000 sq ft) Savings per 1000 sq ft Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO $ 16 $ 21 $ 17 COMBINED NET Savings per 1000 sq ft Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO $ (2) $ 7 $ 23

29 Water Retention Testing

30 Long Term Retention Impacts 8 6 Retention Rate is about 75-80% Drainage (in) Rainfall (in)

31 Vegetative Roof Provides Evaporative Cooling Ambient Temperature (F) Insolation (W/m^2) July 20, 2010 July 27, : 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0: 22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0: Soil Moisture Content (%) Roof Temp (F) : 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0: 22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0:

32 More Recent Work Is simplistic heat transfer model accurate? Does heat transfer into roof deck = heat into space Longer term results (2009 to 2015) Impacts of aging Snow Retention on roof compared to ground Are the roof surfaces different?

33 Temperature (F) A More Detailed Heat Transfer Model Developed EnergyPlus (E+) model of roof assembly with finite difference option (not default CTF) Provides temperatures within layers Provides heat flux at both inside and outside surfaces Massive concrete layer confounds simple method 300 Comparison of Heat Loss through Concrete and Insulation layers Insulation Layer Heat Loss (Wh/m2-day) NRMSE=31.% Concrete Layer Heat Loss (Wh/m2-day) T ro T ri Insulation Layer /1/ :00

34 An Approximate Correction Use a simple mass correction for the concrete layer Demonstrated to work with E+ results Applied correction to the field data Simplified Model (Wh/m2-day) Comparison of Heat Loss through Concrete layer, R22 NRMSE=0.49% Energy Plus Model (Wh/m2-day)

35 Impact of Applying Correction Heat Loss (Btu/ft^2), No Thermal Mass Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO Heat Loss (Btu/ft^2), With Thermal Mass Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO 2010 Htg Season (Oct to April) % 23% -11% 30% 23% -12% 2010 Clg Season (1188.5) (1217.8) (May to Sep) Htg Season (Oct to April) % 30% -14% 37% 24% -13% 2011 Clg Season (1204.4) (1244.9) (May to Sep) Htg Season (Oct to April) % 33% -9% 44% 33% -8% 2012 Clg Season (1333.5) (1352.7) (May to Sep) Htg Season (Oct to April) % 24% -8% 34% 23% -7% 2013 Clg Season (943.2) (928.6) (May to Sep) Htg Season (Oct to April) % 23% -5% 39% 26% -3% 2014 Clg Season (1036.9) (981.1) (May to Sep)

36 Impact of Applying Correction Heating Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO Avg Annual Heat Load (MMBTU per 1000 sq ft) Annual Gas Use (therms per 1000 sq ft) Annual Cost Per 1000 sq ft $ 58 $ 80 $ 73 $ 53 $ 60 $ 82 $ 75 $ 55 saving per 1000 sq ft $ (22) $ (15) $ 5 $ (24) $ (17) $ 3 Cooling Unit 1 Unit 2 Unit 3 Unit 4 Unit 1 Unit 2 Unit 3 Unit 4 4 in EPDM 4 in TPO 4 in Veg 8 in TPO 4 in EPDM 4 in TPO 4 in Veg 8 in TPO Reduced Cooling (ton-hrs/yr per 1000 sq ft) Reduced Cooling Power (kwh/yr per 1000 sq ft) Savings per 1000 sq ft $ 17 $ 21 $ 17 $ 17 $ 21 $ 17 Combined Heat Loss (Btu/ft^2), No Thermal Mass Heat Loss (Btu/ft^2), With Thermal Mass Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO Unit 1 4 in EPDM Unit 2 4 in TPO Unit 3 4 in Veg Unit 4 8 in TPO Net Saving per 1000 sq ft $ (5) $ 6 $ 22 $ (7) $ 4 $ 20

37 Conclusions TPO or cool roof is energy cost neutral in Central NY: benefit in summer, penalty in winter Vegetative roof has cooling season benefit (due to evaporation) More insulation is better (especially in the winter) Vegetative roof retains 75-80% of rainfall